MELISSA BLOCK, HOST:
Dengue fever is something we tend to associate with faraway places, but it's on the rise in the U.S. -southern Florida in particular. Mosquitoes transmit the debilitating disease.
ROBERT SIEGEL, HOST:
One solution is to fight the carriers with other mosquitoes - ones that are genetically modified. And right now, the Food and Drug Administration is deciding whether to approve trials in the Florida Keys of those GMO mosquitoes.
BLOCK: In other countries, these trials have reduced the population of mosquitoes that carry dengue by 90 percent. But in the Keys, as NPR's Greg Allen reports, residents are wary.
GREG ALLEN, BYLINE: There are few places in the country where mosquito control is as critical as the Florida Keys. The Keys are in the southernmost county of the continental U.S. Mosquitoes are a year-round public health problem, and controlling them is a top priority.
MICHAEL DOYLE: This is our hangar and we've got four helicopters in here and two airplanes.
ALLEN: Michael Doyle oversees the Mosquito Control District in the Keys. He's worried about one species in particular - Aedes aegypti. In one of the district's labs, a biologist brings in a wire cage containing Aedes aegypti mosquitoes she's been studying. Doyle puts his hand next to the cage, not touching it. The mosquitoes immediately respond.
They do like people, don't they?
DOYLE: They love people, so if you put your hand up to the screen - I'm not going to touch them because these are wild types so they could be carrying something - but you put your hand up and they'll fly over and land on the screen to try to bite you through the screen.
ALLEN: These are the mosquitoes that carry dengue fever and chikungunya, another tropical disease that swept through the Caribbean and is now showing up in Florida. After years of spraying, Aedes aegypti mosquitoes have developed a resistance in the Keys to most chemical pesticides. Now the Mosquito Control District wants to become the first in the U.S. to try something new - genetically modified mosquitoes. They were developed more than a decade ago by a British company, Oxitec. Trials already conducted in Malaysia, Brazil and the Cayman Islands show releasing bioengineered male mosquitoes can reduce the Aedes aegypti population by 90 percent. Derric Nimmo is overseeing plans to conduct the trials in the Keys. He says only male Aedes aegypti are released.
DERRIC NIMMO: That male when we release it - it mates with the females in the wild and passes on that gene to all the offspring. The female goes off and lays her eggs, the eggs hatch, but then they die before reaching adults.
ALLEN: For the past five years, officials in the Keys have been working with Oxitec to get FDA approval for trials here. The district says surveys it's commissioned of area residents show 60 percent are OK with the trials and 10 to 20 percent opposed. In public meetings though, opposition to the bioengineered mosquitoes has been strong and nearly unanimous. Some residents, like Deb Curley of Cudjoe Key, questioned whether dengue is enough of a problem in the Keys to warrant the trials.
(SOUNDBITE OF ARCHIVED RECORDING)
DEB CURLEY: An investigational trial here - I mean, why here? I mean, I know you're trying to answer that, but it makes no sense to me. We don't want to be guinea pigs.
ALLEN: In 2009 and 2010, Key West was hit with an outbreak of dengue fever - the first in 75 years. There haven't been any cases since, but Doyle compares it to a smoldering fire.
DOYLE: We've had 2.5 to 3 million people that visit the Keys every year. We're very popular. And so the likelihood of it arriving any time is good.
ALLEN: Other residents say they're concerned about how a bioengineered mosquito may affect them and the environment. Here's Key West resident Patty Crimmins.
(SOUNDBITE OF ARCHIVED RECORDING)
PATTY CRIMMINS: We're not particularly thrilled with genetically modified anything.
ALLEN: Derric Nimmo of Oxitec says since Aedes aegypti aren't a native species, removing them would actually be an environmental plus. And, he says, the bioengineered mosquitoes don't live long after they're released.
NIMMO: The insects that we release are designed to just pass on that gene and then the offspring will die. And we've shown that after trials where we start releasing it doesn't last very long in the environment so we've got a very self-limiting, safe, species-specific technology.
ALLEN: The FDA is now considering whether to approve trials of the bioengineered mosquitoes. In the Keys, mosquito control officials say they hope to get approval and begin releasing them this spring. Greg Allen, NPR News, Miami.
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